The present invention relates to the field of high fidelity audio-amplifiers, and more particularly such amplifiers employing digital techniques.
Audio-amplifiers have been marketed in the past, wherein the analog audio signal to be amplified is converted into pulse trains which are modulated in accordance with the analog signal, such pulse trains being amplified by power switching amplifiers, and the output thereof being applied to low-pass filters for reconstructing the audio signal thus amplified. However, the results produced by such amplifiers currently on the market are deemed to be below the level of excellence of sound reproduction desired.
It is an object of the present invention to provide an extremely high fidelity audio-amplifier employing audio signal modulated pulse trains which are amplified to high power output levels, and yet producing very low distortion (less than 0.1%) and a minimal degree of feedback (approximately 22 dB).
In conventional audio-amplifiers, the input and output waveforms are scaled and compared for differences, and these differences are thresholded to achieve distortion detection. In accordance with the amplifier of the present invention, this process is simplified whereby the input audio signal is converted into a sequence of high frequency pulses which control power switches, which in turn apply amplified pulse trains to a reconstruction filter to reconstruct the amplified audio input. The power switches employed for amplification function in a digital manner with their transistors fully saturated or fully cutoff, so as to operate most efficiently, and the various features of the invention result in the aforesaid level of excellence.